The present invention generally relates to a panel for mounting electronic circuit boards and in particular to a panel for mounting electronic circuit boards onto circuit breakers.
As the control circuits utilized within circuit breakers grow in functionality and complexity, the power requirements for the electronics grows and, as a direct consequence, the heat dissipated by the electronics increases. This has made it necessary to provide cooling schemes for the electronics rather than to allow the temperature of the electronic devices to drastically increase, thus preventing early failure of the electronic components.
Previous designs utilized power dissipating devices that were attached to custom blocks of metal, called heat pipes, which in turn were attached to sheet metal panels. The sheet metal panels were generally covered by labels. Heat generated by the power dissipating devices was coupled to the heat pipes through a first thermal junction; the heat was conducted through the heat pipe and then coupled to the sheet metal panel through a second thermal junction. The heat was then conducted through the sheet metal panel, coupled through a third thermal junction to the label material and finally radiated to the air by the label material. These designs were adequate for the level of sophistication and subsequent heat dissipation of the electronics previously required. However, new designs containing more functions require higher computing power microcontrollers and thusly greater efficient cooling schemes are needed to compensate for the higher heat dissipation.
Another problem in providing rigid mounting for electronics is ensuring proper alignment of all mechanical elements of the underlying printed circuit board and the provision of resistance against damage to the board due to vibration. In the past a variety of methods were utilized, all primarily using a collection of mechanical mounting components, i.e. screws, spacers, standoffs, alignment posts, etc. This method of installation was generally very labor and material intensive and alignment of components was not achieved easily.
The electronics within circuit breakers generally contain switches to provide adjustment means. There are usually positions available on those switches that are not intended to be user selectable. It is therefore a requirement to provide a means to physically prohibit these switches from being set into these positions. In the past, either the switch itself was required to contain a stopping mechanism within it or an external stop plate was required to perform this requirement. The switches with the built in stop mechanism are generally more expensive to purchase and installation of the stop plate reduced manufacturing efficiency.
There is also a requirement in the circuit breaker industry to be able to seal the adjustments for the electronic controls from accidental or improper changes. This prevents the operational characteristics of the circuit breaker from being adjusted without the knowledge of that adjustment being evident by the breaking of the seal. In previous generations of electronic circuit breakers, this sealing requirement was met with several custom machine screw parts affixed to the face of the electronic adjustments mounting surface and lead seal wires were threaded through a special path to ensure tampering was clearly visible. These custom parts were expensive to purchase and install.
In order to set the operational characteristics of the circuit breaker, the user must refer to labels installed adjacent to the adjustment switches to determine setting information. Because of the wide range of product lines and subcategories within product lines, there is usually a large number of switches and combinations of labels required. The installation of labels on switches involves two important operations, choosing the proper label combination for the specific product being built and ensuring proper positioning of the label adjacent to the switch. Previous electronic circuit breakers either had separate labels for each type of circuit breaker, thus creating a large inventory of labels or used separate smaller labels pieced together to form the entire electronics label, This latter approach was more inventory efficient but presented a manufacturing problem in ensuring proper alignment of the label to the switch.